Extensive variability of work participation outcomes measured in randomized controlled trials: a systematic review.

Objective: To investigate how work participation outcomes in randomized controlled trials are measured internationally and across disciplines.

Study Design And Setting: We identified trials that reported on work participation in Medline, Embase, PsycINFO and Cochrane Central published between 2014 and 2019. Screening, selection, and data extraction were done by two authors independently. We grouped outcomes into four categories ("employment status", "absence from work", "at-work productivity loss," and "employability") and created subcategories according to how the outcome was measured.

Results: From 10,022 database hits we selected 269 trials reporting on 435 work participation outcomes. Authors used inconsistent outcome terminology to describe the measured constructs. Grouped in four main categories we identified 70 outcomes that reported on "employment status", 196 on "absence from work" and return-to-work, 132 on "at-work productivity loss," and 37 on "employability" outcomes. Variability in measurement methods existed across all categories. Employment status and absenteeism measures consisted mostly of clinimetrically unvalidated tools. "At-work productivity loss" and "employability" were measured by at least 41 different questionnaires.

Conclusion: Extensive variability exists among trials in the measurement of outcomes, measurement methods and measurement instruments that focus on work participation. This study is a first step towards the development of a Core Outcome Set for work participation.